Most solar cookers work on the basic principle: Sunlight is converted to heat energy, that is retained for cooking.

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==Types==

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Below is the basic science for [[solar panel cookers]] and [[solar box cooker]]s. The other main variety of cookers are called [[parabolic solar cooker]]s. They typically require more frequent reorientation to the sun, but will cook more quickly at higher temperatures. They also have the ability to fry foods.

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The three most common types of solar cookers are [[box cookers]], curved concentrators ([[Parabolic cookers|parabolics]]) and [[panel cookers]]. Hundreds — if not thousands — of variations on these basic types exist. Additionally, several large-scale solar cooking systems have been developed to meet the needs of institutions worldwide.

A solar cooker needs an outdoor spot that is sunny for several hours and protected from strong wind, and where food will be safe. Solar cookers don't work at night or on cloudy days, though during the best months for cooking, many foods can be cooked under intermittent clouds or a light haze, as long as food is put out early and there is definitely more sun than not overall.

::[[File:SolSource_Solar_Stove_with_Cookware.gif|thumb|left|250px|[[SolSource]] is an example of a [[parabolic solar cooker]] shown with cookware. The light is focussed at the bottom of the cook pot.]]

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[[File:Industrial_scale_cooking,_Solare_Brucke,_6-10-15.png|thumb|300px|[[Institutional solar cooking]] can employ many large [[parabolic solar cooker|parabolic]] reflectors to generate steam, and cook for thousands of people daily. Many of these systems are in use in [[India]]. This example, was built with technology from [[Solare Brücke]].]]

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===Converting sunlight to heat energy===

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At its simplest, the sunlight-to-heat conversion occurs when photons (particles of light) moving around within light waves interact with molecules moving around in a substance. The rays emitted by the sun have a lot of energy in them. When they strike matter, whether solid or liquid, all of this energy causes the molecules in that matter to vibrate. They get excited and start jumping around. [[Principles_of_Solar_Box_Cooker_Design#Heat_gain|This activity generates heat]].

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[[Image:Parabolic-type.jpg|right|woman with parabolic cooker]]

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Dark surfaces get very hot in sunlight, whereas light surfaces don't. While food cooks best in dark, shallow, thin metal [[pots]] with dark, tight-fitting lids, there are many other containers that can also be used in a solar cooker.

Light passes through the plastic bag or glass cover as a relatively short wavelength. Heat is reflected back as a longer wavelength, and does not easily pass back through the clear enclosure. This explains why cars left in the sun, especially those with blackinteriors, will slowly become hotter and hotter, even on days with low air temperatures.

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===Panel cookers===

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Parabolic solar cookers typically do not require a heat trap, as the light from the reflector is tightly focused on the cook pot. They cook at higher temperatures, but require more frequent reorientation with the sun than box or panel cookers.

Oneormoreshinysurfacesreflectextrasunlightontothepot, increasingits heat potential. Mirrors, aluminumfoil,mylar, mirror-finish metals, chrome sign vinyl, and other shiny materials have all been used successfully for solar cooking, depending on the type of cooker and the environment in which it will be used.

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{{Main|Reflective material}}

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===Fuel:Sunlight===

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==Solarcooker types==

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Sunlightisthe"fuel."A solar cookerneedsanoutdoorspotthatissunny for several hours and protectedfromstrongwind,andwherefoodwillbesafe.Solarcookersdon'tworkatnight or on cloudy days, thoughduringthe best months for cooking,manyfoodscanbecookedunderintermittentclouds or a light haze, as long as food is put out early and there is definitely more sun than not overall. Extra covers or simple foiled boosters can helpundermarginalskies.

Dark surfaces get very hot in sunlight, whereas light surfaces don't. Food cooks best in dark, shallow, thin metal pots with dark,tight-fitting lids to hold in heat and moisture.

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[[Image:Box-type.jpg|right|200px|girl with boxcooker]]

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Box cookers cook food at moderate to high temperatures and often accommodate multiple pots, typically taking between one and three hours to cook various foods. Worldwide, they are the most widespread. There are several hundred thousand in India alone.

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{{Main|Solar box cooker designs}}

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===Retaining heat===

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A transparent heat trap around the dark pot lets in the sunlight, and keeps the heat that is produced from escaping. This is a clear, heat-resistant plastic bag or large inverted glass bowl (in panel cookers) or an insulated box with a glass or plastic window (in box cookers). Curved concentrator cookers typically don't require a heat trap.

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===Capturingextra sunlight energy===

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===<u>Panelcookers</u>===

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One or more shiny surfaces reflect extra sunlight onto the pot, increasing its heat potential. Mirrors, aluminum foil, mylar, mirror-finish metals, chrome sign vinyl, and other shiny materials have all been used successfully for solar cooking, depending on the type of cooker and the environment in which it will be used. See[[Reflectivematerial]].

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[[Image:Panel-type.jpg|right|200px|womanwithpanelcooker]]

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Panel cookers incorporate elements of box and parabolic concentrator cookers. They are simple and relatively inexpensive to buy or produce. Solar Cookers International's "[[CooKit]]" is the most widely used combination cooker.

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{{Main|Solar panel cooker designs}}

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==See Also==

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*[[Principlesof Solar Box Cooker Design]] - ''[[Mark Aalfs]]''

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===<u>Paraboliccookers</u>===

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[[Image:AlSol 1.4.jpg|thumb|300px|An [[AlSol 1.4]] parabolic cooker demonstrates where the cook pot is supported to receive the focussed light from below from the reflector.]] [[Parabolic solar cooker]]s use a bowl shaped reflector to focus the light more directly onto the cook pot, usually from below, and typically do not require a greenhouse enclosure to retain the heat. The parabolic name refers to the shape of the curve of the reflector cross-section.

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They will require more frequent reorientation to the sun, possibly every 10 minutes, but they cook food more quickly at higher temperatures compared to other solar cookers, often reaching over 200°C (400°F). They also have the ability to fry foods. Generally parabolic solar cookers will need to be attended to more than box or panel cookers to avoid possibly burning the food at the bottom of the cook pot. They are especially useful for large-scale institutional cooking.

Contents

Most solar cookers work on the basic principle: Sunlight is converted to heat energy, that is retained for cooking.

Below is the basic science for solar panel cookers and solar box cookers. The other main variety of cookers are called parabolic solar cookers. They typically require more frequent reorientation to the sun, but will cook more quickly at higher temperatures. They also have the ability to fry foods.

A solar cooker needs an outdoor spot that is sunny for several hours and protected from strong wind, and where food will be safe. Solar cookers don't work at night or on cloudy days, though during the best months for cooking, many foods can be cooked under intermittent clouds or a light haze, as long as food is put out early and there is definitely more sun than not overall.

Parabolic solar cookers use a bowl shaped reflector to focus the light more directly onto the cook pot, usually from below, and typically do not require a greenhouse enclosure to retain the heat. They also have the ability to fry and broil foods.

At its simplest, the sunlight-to-heat conversion occurs when photons (particles of light) moving around within light waves interact with molecules moving around in a substance. The rays emitted by the sun have a lot of energy in them. When they strike matter, whether solid or liquid, all of this energy causes the molecules in that matter to vibrate. They get excited and start jumping around. This activity generates heat.

Dark surfaces get very hot in sunlight, whereas light surfaces don't. While food cooks best in dark, shallow, thin metal pots with dark, tight-fitting lids, there are many other containers that can also be used in a solar cooker.

A transparent heat trap around the dark pot lets in the sunlight, and keeps the heat that is produced from escaping. This is a clear, heat-resistant plastic bag or large inverted glass bowl (in panel cookers) or an insulated box with a glass or plastic window (in box cookers).

Light passes through the plastic bag or glass cover as a relatively short wavelength. Heat is reflected back as a longer wavelength, and does not easily pass back through the clear enclosure. This explains why cars left in the sun, especially those with black interiors, will slowly become hotter and hotter, even on days with low air temperatures.

Parabolic solar cookers typically do not require a heat trap, as the light from the reflector is tightly focused on the cook pot. They cook at higher temperatures, but require more frequent reorientation with the sun than box or panel cookers.

One or more shiny surfaces reflect extra sunlight onto the pot, increasing its heat potential. Mirrors, aluminum foil, mylar, mirror-finish metals, chrome sign vinyl, and other shiny materials have all been used successfully for solar cooking, depending on the type of cooker and the environment in which it will be used.

The three most common types of solar cookers are box cookers, curved concentrators (parabolics) and panel cookers. Hundreds — if not thousands — of variations on these basic types exist. Additionally, several large-scale solar cooking systems have been developed to meet the needs of institutions worldwide.

Box cookers cook food at moderate to high temperatures and often accommodate multiple pots, typically taking between one and three hours to cook various foods. Worldwide, they are the most widespread. There are several hundred thousand in India alone.

Panel cookers incorporate elements of box and parabolic concentrator cookers. They are simple and relatively inexpensive to buy or produce. Solar Cookers International's "CooKit" is the most widely used combination cooker.

An AlSol 1.4 parabolic cooker demonstrates where the cook pot is supported to receive the focussed light from below from the reflector.

Parabolic solar cookers use a bowl shaped reflector to focus the light more directly onto the cook pot, usually from below, and typically do not require a greenhouse enclosure to retain the heat. The parabolic name refers to the shape of the curve of the reflector cross-section.

They will require more frequent reorientation to the sun, possibly every 10 minutes, but they cook food more quickly at higher temperatures compared to other solar cookers, often reaching over 200°C (400°F). They also have the ability to fry foods. Generally parabolic solar cookers will need to be attended to more than box or panel cookers to avoid possibly burning the food at the bottom of the cook pot. They are especially useful for large-scale institutional cooking.